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Re: pushing a variac

>>From uucp-1.csn-dot-net!smtpgate.whitlock-dot-com.!RICHARDH-at-whitlock-dot-com Thu Apr
>>4 13:15 MST 1996
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>>12:50:15 -0700
>From: Richard Hull <whitlock-dot-com!RICHARDH-at-uucp-1.csn-dot-net>
>To: tesla <tesla-at-grendel.objinc-dot-com>
>Subject: Re: pushing a variac
>Date: Thu, 04 Apr 96 14:49:00 PST
>Encoding: 59 TEXT
>
>
>Kevin and Jerry,
>
>I have the ratings charts for  most powerstat products and they have a full
>graph of the overload capabilities and with a smooth load (resistive) it can
>be easily overload to 3X the normal rating for a minute with no ill effects
>That's 84 amps!  With forced air cooling, the unit can be pushed longer.
> Amazingly the unit is rated to 2X its rated current (56 amps) for 5 minutes
>in open air!  The brushes are the weak link in the chain and the varying
>inductive load presented by a transformer would limit the general usage to
>2X with forced air I woud think.  I use a 50 amp powerstat system and have
>run up to 100 amps through it for 7 minutes, no air cooling, with only
>moderate warming following the run.
>
>Richard Hull, TCBOR
> ----------

I wasnt saying that you cant push a variac beyond it's rated limits without
oil, it is just that if you do immerse it in oil, you can run 2 to 3 times
the current continiously with no ill effects. I think I saw something about
it about 6 months ago on the other tesla list serv.

-Jerry

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